Help the Oppressor
Prophet Muhammad (peace be upon him) said:
انْصُرْ أَخَاكَ ظَالِمًا أَوْ مَظْلُومًا
"Help your brother whether he is an oppressor or oppressed,"
One of the Sahabah replied saying:
يَا رَسُولَ اللَّهِ أَنْصُرُهُ إِذَا كَانَ مَظْلُومًا، أَفَرَأَيْتَ إِذَا كَانَ ظَالِمًا كَيْفَ أَنْصُرُهُ
"O Allah's Messenger (ﷺ)! I will help him if he is oppressed, but if he is an oppressor, how shall I help him?"
To which the Prophet Muhammad (peace be upon him) retorted:
تَحْجُزُهُ أَوْ تَمْنَعُهُ مِنَ الظُّلْمِ، فَإِنَّ ذَلِكَ نَصْرُهُ
"By preventing him from oppressing (others), for that is how to help him."
- Reported in Saheeh al-Bukhari.